If your app or site hasn't been on larger infrastructures before, you'll need to make sure it can scale well. Dedicated hosting tends to encourage coders to build for a fixed number of machines, but cloud hosting needs a more scalable approach. If you're scaling on demand, the number of machines can shrink and grow automatically, so your app needs to be able to cope with this from the ground up.

This is a big area, so the best approach is to fire up a few instances on EC2 and find out whether it scales. It's possible to rehearse for any eventuality, which is useful when running sites and apps prone to spikes in traffic. Test instead of guess.

This ability to rapidly scale your application and have the privilege to instantly throw dozens of servers at a problem aren't things that anyone had the luxury of until cloud computing became available.

The cost of scaling at short notice is also surprisingly cheap. Amazon provides backup onto the cloud through its S3 service (Secure simple storage). Rather than backing up your data once, S3 makes six copies, all in different locations on different hard disks. S3 can be combined with EC2, meaning that you can turn servers on and off with unprecedented ease and can cater for any eventuality, both planned and unforeseen.

Cloud hosting makes it entirely possible for serious e-business to be within reach of any developer with ideas. The set-up cost of a cloud server running on Amazon is 10 cents plus a valid credit card. From this initial set-up, you can scale up to running many, many different instances of the server – with no additional lead time or further contracts to delay the process.

Benefits to business

The implications of this are already benefiting a large number of businesses that, without this low cost of entry, simply wouldn't exist. For instance, in December 2007 the social networking games company Playfish launched a game called Who Has The Biggest Brain?

Since then Playfish has grown exponentially. It's currently responsible for most of the top ten games on Facebook and provides games to more than 50 million users. Scaling an operation such as this using a traditional set-up would have been prohibitively expensive and unreliable. With user numbers increasing by up to one million in the space of 24 hours, there would have been moments of poor service and downtime where the infrastructure just couldn't cope. Not only did cloud hosting make the initial outlay affordable, it made the entire solution more agile and made scaling more responsive.

The traditional way of scaling often either overcaters or under-caters for demand. The lead times involved in setting up, getting the capital expenditure authorised, even configuring the new boxes the same as the existing ones, all introduce unnecessary delay. It's a constant game of cat and mouse between demand and capacity.

Coping with demand

With cloud hosting, you don't need to worry about any of that. A new server can be powered up in a matter of minutes and configured exactly the same as your existing one using a simple configuration tool. Similarly, if your demand falls off, you can turn these extra boxes off as easily as you turned them on. Cloud computing takes the infrastructure and scaling costs out of professional hosting.

As such, the ground is fertile for new web ideas that previously just wouldn't have been possible. Just like open source software, cloud hosting reduces the cost of failure. Everything as a service With storage, backups, music and even operating systems such as GOs (thinkgos.com) being run as a service, personal computers will become smaller, lower spec and ultimately cheaper.

There's less for them to do, as everything is done on the cloud. This phenomenon is known as thin-client computing – we'll able to run all of the apps we currently run on our laptops and PCs on the cloud. Gartner has predicted that worldwide netbook sales will grow from just over 5million in 2008 to 7.8million in 2009. That's more than 50 per cent growth, compared to a predicted 15 per cent growth for the entire laptop market and an overall decline in sales for desktop PCs.

Music need no longer take up bags of valuable space on your hard drive. Ownership is old hat. Run your digital life as a service. There's just no escaping the cloud!

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First published in .net Issue 189

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